* Attack on central state spreads war of attrition
* Insurgents controlled central Um Rawaba for hours
* Government says back in control of city, situation
The line of army pickup trucks rumbled into the dusty streets of Um Rawaba, a once placid city in the heart of Sudan that days ago became a new front in the war of attrition between government and rebels.
Six days earlier, hundreds of insurgents had stormed in, spraying bullets and killing up to 13 civilians and soldiers, before pulling out as government planes started flying overhead.
A week on, Um Rawaba's traders and shoppers cheered and gave "thumbs-up" signs as the latest government reinforcements arrived and drove past buildings still bearing the scars of the attack.
Even as government minders looked on, some citizens acknowledged they were worried.
"This was the first time we had such an attack ... We want security," trader Omar Kuf told Reuters on Thursday.
Sudan has long been plagued by rebel attacks - but there were at least two main reasons for the Khartoum government to sit up and take particular notice after this assault.
Almost all the past turmoil has sprung up in the country's distant and arid peripheries, not in North Kordofan, the region that includes Um Rawaba and forms part of Sudan's commercial heartland, a hub for its agriculture, livestock and gum arabic industries.
Second, many of the earlier uprisings have been focused affairs - between the government and rebels fighting over grievances in their particular territories, among them Darfur, South Kordofan and Blue Nile.
But this was a coordinated attack by members of those rebel groups, fighting together under the single banner of the Sudanese Revolutionary Front (SRF) with a nation-wide agenda.
It was biggest assault yet by the umbrella group of fighters who have vowed to topple President Omar Hassan al-Bashir and end what they see as his elite's stranglehold on the whole country - an accusation he denies.
The government has previously played down the threat posed by the rebels, and called Um Rawaba's attackers "terrorists" holding civilians as "human shields".
Diplomats and analysts said the raid on Um Rawaba appeared to be a bid to stretch Sudan's army ever thinner, across an ever-changing line of battle in Sudan's savannahs and scrublands, rather than an attempted land grab.
"They now feel the government forces are weak, that they can strike anywhere," said Faisal Saleh, a Sudanese journalist.
Bashir, in power since 1989, has been facing small street protests over an economic crisis and also dissent inside the army and his ruling circles.
One of SRF's member groups - Darfur's Justice and Equality Movement (JEM) - has already shown its ability to spread chaos beyond its home territory by launching an unprecedented assault on Khartoum in 2008.
The attack on Um Rawaba, North Kordofan's second biggest city, 500km (300 miles) south of the capital, was much larger than initial reports indicated, officials said.
"They came with 140 cars, each manned with between four and six people," said Um Rawaba commissioner Sharif Fadhil, who, like other local officials, said the situation was now under control.
In the first official toll, Fadhil said 13 civilians and soldiers had been killed. Four other people died in other areas that the rebels had also attacked, officials said.
"Life returned to normality within 48 hours. Now life here will be better than before," said Adam Abdallah, head of a union representing local workers. "The army has spread out everywhere. Citizens stand by the government, army and authorities."
Around 19,000 people in North and South Kordofan have been affected or displaced by the fighting since Saturday, Haroun Abdallah, the government's humanitarian aid commissioner for South Kordofan, said by phone.
Security was tight in Um Rawaba on Thursday. Army trucks with mounted machine-guns were parked in front of all government buildings.
But something like normal life had returned to the streets. Women shopped in the packed market and men drank tea in the shade of makeshift cafes.
Outside the city, a backup transformer at the main power plant had been connected after the old one was set ablaze by the attackers.
"We are happy that power is back and shops open," said Khalid Ezzedin, speaking again in the presence of government minders. "We demand security from the government."